There are numerous devices and applications which are based on transferring Voice and/or Video over IP (Internet Protocol). These include having VoIP clients on a PC, or installed on any other communication device, such as a mobile phone. There are also dedicated Wi-Fi telephones which support VoIP applications; VoIP telephones can be both wired, such as the Cisco CP-7941G, or wireless, such as the Polycom SPECTRALINK® 8002 2200-37010-020 or Linksys WIP310-G1.
Client devices for making and receiving voice and video calls over the IP network with the standard functionality of most “original” telephones are also referred to as “softphones”. Softphones usually allow integration with IP phones and USB phones instead of utilizing a computer's microphone and speakers (or headset). Often a softphone is designed to behave like a traditional telephone, sometimes appearing as an image of a phone, with a display panel and buttons with which the user can interact.
A typical application of a softphone is to make calls via an Internet telephony service provider to other softphones or to telephones. Popular Internet telephony service providers include SKYPE®, GOOGLE TALK™, and VONAGE®, which have their own softphones that a user may install on his computer or the like. Most service providers use a communication protocol called SIP (Session Initiation Protocol), whereas SKYPE® has a closed proprietary system. In order to make a voice call over the internet, one should have any computing device with an audio input (e.g. microphone) and output means (e.g. a speaker or headset), Internet connectivity such as DSL, Wi-Fi, cable or LAN, and an account with an Internet telephony service provider or IP PBX.
Such prior art devices establish a single connection to the Internet telephony service provider.